1. Field of the Invention
The present disclosure relates to light sources, and more particularly, to a method of driving a light source used in a liquid crystal display (LCD) apparatus, a light source apparatus for performing the method and a display apparatus having the light source apparatus.
2. Discussion of the Related Art
Generally, LCD devices have thinner thickness, lighter weight, lower driving voltage and lower power consumption as compared to other display devices, such as cathode ray tube (CRT) devices and plasma display panel (PDP) devices. As a result, LCD devices are widely employed for various electronic devices such as monitors, laptop computers, cellular phones, and the like. The LCD device typically includes an LCD panel that displays images using a light-transmitting ratio of liquid crystal molecules and a backlight assembly disposed below the LCD panel to provide the LCD panel with light.
The LCD panel includes an array substrate, an opposite substrate and a liquid crystal layer. The array substrate includes a plurality of signal lines, a plurality of thin-film transistors (TFTs) and a plurality of pixel electrodes. The opposite substrate faces the array substrate and has a common electrode. The liquid crystal layer is interposed between the array substrate and the opposite substrate.
The backlight assembly has employed a plurality of cold cathode fluorescent lamps (CCFLs) as a light source. However, recently, light-emitting diodes (LEDs) have been employed for the backlight assembly for low power consumption and high color reproducibility.
The LCD device further includes a driver and a controller to drive the backlight assembly. The controller controls the driver using high speed pulse width modulation (PWM) to control the amount of light from the LEDs. The PWM control methodology provides a static current to the LEDs through pulse generation, pulse width comparison and modulation.
The LEDs typically include a red (R) LED, a green (G) LED and a blue (B) LED, collectively known as RGB LEDs. Red light, green light and blue light emitted from the RGB LEDs, respectively, is mixed to provide white light. However, the luminance characteristics of the individual LEDs may vary in accordance with usage time and the temperature of the LED surroundings, such that a white balance may not be achieved.
To address the issue of white balance, the backlight assembly detects the amounts of light by using a color sensor having a sensitivity of wavelengths corresponding to each of the RGB LEDs. That is, the backlight assembly detects the amounts of RGB light by using RGB color sensors, and provides the controller with detected amounts of light. The controller compares the detected amounts of light with light information stored in a look up table (LUT), and calculates a compensating value. To control the luminance of the RGB light, the controller would feedback a PWM signal for each of the RGB light to the driver based upon the calculated compensating value.
However, when the LEDs deteriorate, the amount of light generated from the LED exceeds a control range of the controller such that an accurate control is unable to be effectively carried out.